The present invention relates to providing services to clients and, more specifically, to providing clients with services that retrieve data from data sources that do not necessarily support the format required by the clients.
The World Wide Web includes a network of servers on the Internet, each of which is associated with one or more HTML (Hypertext Markup Language) pages. The HTML pages associated with a server provide information and hypertext links to other documents on that and (usually) other servers. Servers communicate with clients by using the Hypertext Transfer Protocol (HTTP). The servers listen for requests from clients for their HTML pages, and are therefore often referred to as xe2x80x9clistenersxe2x80x9d.
Users of the World Wide Web use a client program, referred to as a browser, to request, decode and display information from listeners. When the user of a browser selects a link on an HTML page, the browser that is displaying the page sends a request over the Internet to the listener associated with the Universal Resource Locator (URL) specified in the link. In response to the request, the listener transmits the requested information to the browser that issued the request. The browser receives the information, presents the received information to the user, and awaits the next user request.
Traditionally, the information stored on listeners is in the form of static HTML pages. Static HTML pages are created and stored at the listener prior to a request from a web browser. In response to a request, a static HTML page is merely read from storage and transmitted to the requesting browser. Currently, there is a trend to develop listeners that respond to browser requests by performing dynamic operations. For example, a listener may respond to a request by issuing a query to a database, dynamically constructing a web page containing the results of the query, and transmitting the dynamically constructed HTML page to the requesting browser.
Another trend is to expand Internet access to devices other than conventional computer systems. For example, wireless phones have been developed that include embedded web browsers. Due to size and cost constraints, the xe2x80x9cmicro browsersxe2x80x9d contained in these devices have very limited functionality relative to the browsers that have been developed for full-fledged computer systems. However, devices with embedded micro browsers are usable in circumstances under which using a conventional computer system is impractical. In addition to having an embedded micro browser, certain wireless phones support a two-way paging protocol known as Short Message Stimulator (SMS). Using SMS, an SMS-enabled phone may send a text message to another SMS-enabled phone.
A typical system in which web-enabled, SMS-enabled phones may be used is illustrated in FIG. 1. Referring to FIG. 1, system 100 includes a wireless phone 102 connected to a network 104 though a wireless communication medium. Network 104 may be, for example, a global digital network such as the Global System for Mobile Communications (GSM) network. SMS messages from the phone 102 may be sent through the network 106 to a gateway 106 that includes a translator 112. Gateway 106 may be, for example, a NAMP server, available from Nokia, that is configured to translate SMS messages to HTTP messages that can be sent over an IP network. In the illustrated embodiment, gateway 106 translates SMS messages from phone 102 and transmits them using HTTP over the Internet 108 to a web server 110.
In response to the HTTP request from gateway 106, web server 110 sends a web page back over the Internet 108 to gateway 106. Gateway 106 converts the web page to an SMS message and sends it to phone 102 through network 104. Unfortunately, due to the limited capabilities of phone 102, the process of intelligently converting the web page into something that can be delivered to the phone 102 can be extremely difficult.
According to one approach, gateway 106 includes filtering logic that is programmed with web-page-specific filtering rules. Such a filtering rule may indicate, for example, that text that is to be included in the SMS message sent back to the phone 102 is to be obtained by extracting the 53 characters that follow a particular sequence of tags within the web page associated with the rule. The rule for a different web page could specify completely different criteria for located and extracting text. Even for the same web page, a particular filtering rule may cease to yield the desired result if the content or format of the web page changes. Consequently, using the web-page-specific filtering rule approach places an enormous burden on the manager of gateway 106 to design the various filter rules and to keep them up to date for all pages that will be requested through gateway 106.
In an alternate approach, the filtering functionality is moved outside of gateway 106 into a filtering box that is placed between the gateway 106 and the Internet 108. The gateway 106 continues to believe that it is interacting with the web servers over the Internet 108, and continues to translate between HTTP and SMS. However, all HTTP traffic sent to or sent from gateway 106 actually passes through the filtering box. The filtering rules applied by the filtering box may be specified by users themselves. Thus, the filtering box may filter the same web page differently for different phone users based on how those phone users have designed their filters. While this approach reduces the managerial burden of the gateway administrator, it largely shifts that burden to the users themselves. Further, it only allows the phones to communicate with one type of data source: HTTP servers. Other information sources, such as database systems, are not made accessible to phone 102 by the gateway 106.
Based on the foregoing, it is clearly desirable to improve the techniques by which users of less-conventional clients gain access to the World Wide Web. It is further desirable to provide techniques that allow such clients to conveniently access other sources of information.
A method and system are provided for allowing clients to retrieve data from data sources that do not necessarily support the same protocols and formats as the clients. According to one aspect of the invention, a pre-processor responds to the service requests of clients by generating request objects. In one embodiment, the request objects are XML-structured documents with unresolved links to the data sources that have information required by the clients. An XML processor resolves the links by issuing requests through one or more gateways. The gateways convert the responses received from the data sources into XML, which the XML processor uses to create XML composite response documents. A post-processor filters the XML response documents, and applies XSL stylesheets to transform the XML composite response documents into client-specific responses that conform to the format required by the clients. The client-specific responses are then sent to the clients.